Precise bone opening requires a reliable reference in position and direction which a surgeon with a drill or cutter can use as a guide. It is known that guide wires which are inserted (drilled or tapped) into the femur prior to drilling in order to guide the drill safely are used for this purpose.
U.S. Pat. No. 6,074,392 describes such a curved positioning and insertion instrument for inserting a guide wire into the femur, comprising a curved guide tube having a distal end for placing on the trochanter and a proximal end for pushing in a guide wire, comprising a retaining arm for the connection between the guide tube and a handle. This design has been chosen because the insertion of a guide wire along a curve is advantageous with regard to the anatomy of the human femora, and the tissue in the affected region is therefore impaired to a lesser extent during an operation.
U.S. Pat. No. 6,074,392 therefore describes an instrument design comprising a key element which consists of a curved guide tube for a curved guide wire. This guide wire is inserted into the bone and serves as a guide path for a hollow and flexible drill. The guide wire is mounted with the aid of a positioning and insertion instrument, the curved guide tube being mounted by means of a support part on a handle which can be properly held by the surgeon. The exact positioning of the guide tube is implemented by means of X-rays or by direct inspection. After positioning, the guide wire is hammered in along the longitudinal axis of the bone or driven in in another manner. Thereafter, the insertion instrument is removed and the flexible drill or cutter is passed over the guide wire. After drilling is complete, everything is removed.
However, the weak point of this solution is that there is no particular possibility for correction if the X-ray image shows that the guide wire is not optimally positioned.
In a completely different design, for example according to U.S. Pat. No. 5,951,561, a guide instrument which has the possibility of correction of guide wires is also described. However, this design consists of a bulky sheath which receives a rotary cylindrical component comprising a plurality of discs each having a plurality of holes, which have to be oriented concentrically with one another in a complicated production process and in addition provide no possibility for tapping a guide wire along a curve into the femur. To this extent, this design offers no improvement for a design according to the generic type.
It is now the object of the invention to permit corrections by means of a simple device, the intention being to impair the tissue in the affected region as little as possible. For this reason, as already noted above, the person skilled in the art would not at all have used U.S. Pat. No. 5,951,561 as prior art for achieving the present object. It is also comprehensible that U.S. Pat. No. 6,074,392 published in 1998 is itself a further development of U.S. Pat. No. 5,624,447 published in 1997, while U.S. Pat. No. 5,951,561 was published in the same year as U.S. Pat. No. 6,074,392 and therefore followed another parallel route for setting guide wires.
Further but less relevant documents relating to the prior art are U.S. Pat. Nos. 4,466,429; 3,439,671; 5,135,527; 5,112,336; 4,712,541; and 6,273,892.